Process for straightening keratin fibres with a heating means and denaturing agents

ABSTRACT

The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 14/295,435, filed Jun. 4,2014, which is a divisional of application Ser. No. 13/369,516, filedFeb. 9, 2012, now U.S. Pat. No. 8,765,107, which is a continuation ofapplication Ser. No. 12/302,252, filed May 18, 2009, now abandoned,which was a national stage of International Application No.PCT/FR2007/000870, filed May 23, 2007, which claims the benefit ofFrench Patent Application No. 0651911, filed May 24, 2006, and thebenefit of U.S. Provisional Application No. 60/814,529, filed Jun. 19,2006, all of which are incorporated herein by reference.

The invention relates to a process for relaxing keratin fibres with aheating means and at least two denaturing agents.

The relaxing process according to the invention is performed withoutusing a reducing agent or a lanthionization agent. It does not compriseany reducing or lanthionizing step.

According to the invention, the term “keratin fibres” means fibres ofhuman or animal origin such as head hair, bodily hair, the eyelashes,wool, angora, cashmere or fur. Although the invention is not limited toparticular keratin fibres, reference will nevertheless be made moreparticularly to head hair.

According to the invention, the term “relaxing” covers the relaxing,straightening or uncurling of Caucasian or African hair.

The term “denaturing agent” means a compound of organic or mineralorigin containing both at least one electron-donating site of basic ornucleophilic nature and at least one electron-accepting site of acidicor electrophilic nature, which interacts with the weak bonds of keratin.

According to the invention, a denaturing agent is a compound capable ofreducing the optical rotation of a model protein, for instance bovineserum albumin, by at least 7° and/or 5° at 579 nm, the measurementsbeing taken after incubation for 3 hours at 37° C., using a polarimeter,as described in Biochemistry 2 (1), 47-57, 1963:

-   -   either in TRIS 0.05 M pH 7.6 buffer    -   or in a 5.45 M urea solution when the solubility of the compound        is insufficient in the TRIS 0.05 M pH 7.6 buffer.

The compound is considered as being a denaturing agent according to theinvention if the reduction of the optical rotation is at least 7° inTRIS 0.05 M pH 7.6 buffer and/or at least 5° in 5.45 M urea solution.

The term “weak bonds of keratin” means all the non-covalent bonds suchas:

-   -   the saline bonds resulting from coulombic interactions between        the functional groups present on the side chains of amino acids    -   the hydrogen bonds that become established between amino acids        especially via oxygen and hydrogen atoms    -   the hydrophobic bonds resulting from the tendency of the        non-polar chains of amino acids to associate in order to        minimize the contacts with water.

The term “heating means” means any means for heating keratin fibres to atemperature of at least 110° C., such as heating irons, for example flator round irons, microwave generators or sources of infrared radiation.

Two techniques are used for permanently reshaping the hair. They arebased on cleavage of the disulfide covalent bonds present in keratin(cystine):

-   -   the first consists, in a first stage, in performing this opening        of the disulfide bonds using a composition containing a reducing        agent, and then, after having preferably rinsed the hair, in        reconstituting the said disulfide bonds in a second stage, by        applying to the hair, which has been placed under tension        beforehand with rollers or the like or shaped or straightened        out by other means, an oxidizing composition also known as a        fixer, so as to give the head of hair the desired shape. This        technique makes it possible either to make the hair wavy or to        relax it, uncurl it or straighten it out;    -   the second consists in performing a “lanthionization” operation        using a composition containing a base belonging to the hydroxide        family. This leads to replacement of the disulfide bonds        (—CH2-S—S—CH2-) with lanthionine bonds (—CH2-S—CH2-). This        lanthionization operation involves two consecutive chemical        reactions:    -   the first reaction consists of a beta-elimination on cystine        brought about by a hydroxide ion, leading to the cleavage of        this bond and to the formation of dehydroalanine:

-   -   the second reaction is a reaction of dehydroalanine with a thiol        group. Specifically, the double bond of the dehydroalanine        formed is a reactive double bond. It can react with the thiol        group of the cysteine residue that has been released to form a        new bond referred as a lanthionine bridge or bond or residue.

Relative to the first technique using a reducing agent, thislanthionization technique does not require a fixing step, since theformation of the lanthionine bridges is irreversible. It is thusperformed in a single step and makes it possible either to make the hairwavy, or to relax it, uncurl or straighten it out. However, it is mainlyused for relaxing naturally curly hair.

For the first technique, the reducing compositions generally used forthe first step of a permanent-waving or hair-relaxing operation containthiols, sulfites or bisulfites as reducing agent. These agents aregenerally used in essentially aqueous medium at concentrations ofbetween 0.5 and 1 M to obtain good opening of the disulfide bonds. Amongthe thiols, those commonly used are thioglycolic acid, cysteamine,glyceryl monothioglycolate, thiolactic acid and cysteine. Thioglycolicacid is particularly efficient at reducing the disulfide bonds ofkeratin at alkaline pH, especially in the form of ammoniumthioglycolate, and constitutes the product most frequently used inpermanent-waving (“hair waving”). It has been found, however, thatthioglycolic acid must be used in sufficiently basic medium (in practiceat a pH of between 8.5 and 9.5) if curling of satisfactory intensity isto be obtained. Besides the drawback of releasing an unpleasant odourrequiring the use of more or less efficient fragrances to mask theodours, the use of a thiol at alkaline pH also results in degradation ofthe fibre and most particularly in impairment of artificial colorations.

Sulfites or bisulfites are mainly used for relaxing the hair. They havedrawbacks similar to those of thiols, with lower efficacy.

Thiols and sulfites (or bisulfites) also have the drawback of havingpoor stability in aqueous solution.

In general, the durability of the reshaping effects obtained with thiolsand sulfites by reduction of disulfides following by fixing is judged tobe very much lower than that which may be obtained via thelanthionization technique.

For the second technique, the compositions generally used to performlanthionization contain as base a hydroxide such as sodium hydroxide,guanidinium hydroxide or lithium hydroxide. These lanthionization activeagents, which allow opening of the disulfide bonds via abeta-elimination mechanism, are generally used as a water-oil emulsionat concentrations of between 0.4 and 0.6 M, by leaving them to actgenerally for 10 to 15 minutes at room temperature. Sodium hydroxideremains the agent most frequently used. Guanidinium hydroxide is now thepreferred compound for many compositions. These two hydroxides, sodiumhydroxide and guanidinium hydroxide, are the two main agents used forthe relaxing or uncurling of naturally curly hair. They have severaladvantages over ammonium thioglycolate and sulfites, in particular theabsence of unpleasant odour, the fact that only one operating step isrequired (shorter treatment time) and much greater durability andefficacy of reshaping of the hair.

However, these hydroxides have the major drawback of being caustic. Thiscausticity affects the scalp by causing irritation, which isoccasionally severe. This may be partially remedied by applyingbeforehand to the scalp fatty protective cream often referred to as a“base” or “base cream”, the word “base” in this case not having themeaning of a basic agent in the chemical sense. When the protectivecream is combined with the hydroxide in a single composition, it isgenerally referred to as “no-base”, as opposed to the above name. This“no-base” technique is preferred.

The causticity of hydroxides also affects the state of the hair byfirstly giving it a coarse feel and secondly making it much morebrittle, this brittleness possibly going as far as crumbling or breakingor even dissolution of the hair if the treatment is prolonged. Incertain cases, hydroxides also cause decoloration of the natural colourof the hair.

Formulations containing sodium hydroxide are generally referred to as“lye relaxers” and those not containing it are referred as “no-lyerelaxers”.

The main relaxing formulations known as “no-lye” relaxers useguanidinium hydroxide. Since guanidinium hydroxide is unstable, it isgenerated at the time of use by mixing guanidinium carbonate and asource of sparingly soluble hydroxide such as calcium hydroxide. Thereaction between these two compounds leads to the formation ofguanidinium hydroxide and calcium carbonate, which precipitates in thecomposition. The presence of this precipitate makes the final rinsing ofthe hair much more difficult and leaves mineral particles on the hairand the scalp, which give it a coarse feel and an unaesthetic appearanceresembling dandruff. The recent success of guanidinium hydroxide(“no-lye”) over sodium hydroxide (“lye”) appears to arise from betterrelaxing efficacy and better skin tolerance. However, these techniquesusing bases of the hydroxide family remain very aggressive to the hairand the scalp and require very strict control of the duration ofapplication to avoid excessive irritation and impairment of the hairthat may go as far as breakage. This aggressiveness arising from thecausticity of hydroxides is justification for not using these hairlanthionization compositions for permanent-waving (hair waving), butsolely for hair straightening or hair relaxing.

Furthermore, hydroxides are known to be good agents for hydrolysingamide functions (cf. for example March's Advanced Organic Chemistry, 5thedition, Wiley Interscience, New York, “Hydrolysis of Amides” page 474et seq.), which thus lead to cleavage of peptide bonds by directnucleophilic attack. It is thus probable that the observed impairmentsof the hair and of keratin materials in the broad sense are largely dueto partial hydrolysis of the amide bonds of keratin.

There is thus a real need for relaxing compositions that are markedlyless aggressive to the hair.

Various studies have been conducted in order to overcome both thedrawbacks of reducing agents (first technique) and/or those ofhydroxides (second technique).

Thus, many reducing agents have been proposed to replace thioglycolicacid, but thioglycolic acid in the form of ammonium thioglycolateremains both the reference compound and the compound most widely used incosmetic formulations, not only for shaping but also for straighteningthe hair.

It has also been proposed in numerous patents to combine common reducingagents (thiols, sulfites or bisulfites) with urea or alkyl ureas toreduce the irritation and damage caused to the hair, not only forshaping but also for relaxing. Mention will be made, for example, of:

-   -   patent application CA 1315204, which describes a composition        containing ammonium thioglycolate (5.5-11.5%) and urea or a        monoalkyl urea (1-3%) for shaping the hair,    -   patent application U.S. Pat. No. 3,847,165, which describes a        composition containing ammonium thioglycolate (1.2-1.4 M) and        urea (2.0-2.7 M) for shaping the hair at an acidic pH,    -   patent application NL 6410355, which describes a composition        containing a sulfite (0.8-1.5 M) and urea (0.6-3.0 M) for        shaping and relaxing the hair,    -   patent application JP 2000/229 819, which describes a        composition containing a sulfite or bisulfite (0.5-15%), urea        (0.5-15%) and an alcohol (ethanol and/or isopropanol, 1-30%) for        shaping and relaxing the hair.

It has also been proposed in numerous patents to combine hydroxides,serving as lanthionization active agent, with certain additivesgenerally serving to protect the hair. Mention will be made, forexample, of:

-   -   patent application WO 2002/003 937, which describes a        composition containing C3-05 monosaccharides,    -   patent application WO 2001/064 171, which describes a        composition containing complexing agents,    -   U.S. Pat. No. 5,641,477, which describes a composition        containing a hydrogenated starch hydrolysate,    -   patent application WO 02/085 317, which describes a composition        containing organic nucleophiles that react during the second        step with the dehydroalanine formed with hydroxides, to give new        bridges.

Although all these proposals lead to more or less pronouncedimprovements, they are not able to sufficiently reduce the damageassociated with the very causticity of hydroxides.

As indicated previously, the use of reducing agents leads to poordurability of the relaxing or straightening of the hair and the use ofhydroxides, on account of their causticity, limits their use in thefield of hair relaxing.

The use of resorcinol at a concentration of 40% and at a pH of 7 forrelaxing the hair has been reported by M. Wong et al.: M. Wong, G.Vis-surel, and J. Epps J. Soc. Cosmet. Chem. (1994), 45, 347-352.However, the tests that we have performed under these conditions onnaturally curly African hair do not relax it, but lead, at the verybest, to slight uncurling.

After considerable studies, it has now been discovered, entirelysurprisingly and unexpectedly, that hair can be durably relaxed bycombining the action of at least two denaturing agents and of a means ofheating to a temperature above 110° C. Excellent results in terms ofrelaxing, cosmetic properties of the hair and fibre integrity are thusobtained.

Without being bound by theory, the Applicant considers that there is acombined action, on the keratin fibres, of at least two denaturingagents and of a heating means, which allows the fibres to be efficientlyand durably relaxed.

The Applicant has found that it is possible to overcome the drawbacks ofthe prior art and to satisfy the abovementioned objectives by performinga process for relaxing keratin fibres, comprising:

-   -   a step of applying to the keratin fibres a hair-relaxing        composition containing at least two denaturing agents,    -   a step of raising the temperature of the keratin fibres, using a        heating means, to a temperature of between 110 and 250° C.

Advantageously, the denaturing agents have a molar mass of greater than18.1 g/mol and preferably between 40 and 600 g/mol.

Preferably, the hair-relaxing composition comprises an overallconcentration of denaturing agents of between 1 M and 8 M and moreadvantageously between 2 M and 8 M of the said denaturing agents; thiscorresponds to a weight concentration of between about 6% and about 80%and more advantageously between about 12% and about 80%, relative to thetotal weight of the composition, of the said denaturing agents.

Advantageously, the temperature is raised using a heating means to atemperature of between 120° C. and 220° C. and more advantageouslybetween 140° C. and 220° C.

According to one embodiment, the said composition is applied to wetkeratin fibres.

A step intended to remove the excess composition, for example using atowel, may also be introduced between the step of applying thecomposition and the step of raising the temperature.

Preferably, the denaturing agents are chosen from protein-denaturingagents such as:

-   -   ureas,    -   guanidines,    -   α-hydroxy acid and α-keto acid derivatives,    -   mono-, di-, tri- or polyhydroxylated aromatic derivatives,    -   cyclic or linear amides,    -   surfactants or detergents, especially those containing sugar or        choline or deoxycholine or polyethylene glycol units, such as        the following compounds:    -   acetobromo-α-D-glucose    -   taurodeoxycholic acid sodium salt    -   N-octyl-β-D-glucopyranoside    -   MEGA-8    -   N-hexyl-β-D-glucopyranoside    -   N-heptyl-β-D-thioglucopyranoside    -   N-heptyl-β-D-glucopyranoside    -   glycodeoxycholic acid sodium salt    -   sodium deoxycholate    -   sodium cholate    -   CHAPSO    -   CHAPS    -   octaethylene glycol mono-N-dodecyl ether    -   N,N′-bis(3-D-gluconamidopropyl)cholamide    -   polyoxyethylene (23) lauryl ether C12E23    -   nonaethylene glycol monododecyl ether    -   cetrimide    -   decyl glucoside    -   decyl maltoside    -   N,N-bis(3-D-gluconamidopropyl)deoxycholamide    -   digitonine    -   dodecyl maltoside    -   dioctyl sodium sulfosuccinate    -   lauryldimethylamine oxide    -   octaethylene glycol isotridecyl ether    -   glycocholic acid, sodium salt    -   sodium lauryl sulfate    -   octanoyl-N-methylglucamide    -   nonanoyl-N-methylglucamide    -   decanoyl-N-methylglucamide    -   nonyl glucoside    -   nonaethylene glycol octylphenyl ether    -   octyl thioglucoside    -   polyethylene polypropylene glycol    -   monosodiumtaurocholic acid    -   nonaethylene glycol octylphenol ether    -   polyoxyethylene sorbitan monolaurate    -   polyoxyethylene sorbitan monooleate    -   N-octylsulfobetaine    -   N-decylsulfobetaine    -   N-dodecylsulfobetaine    -   N-hexyldecylsulfobetaine,    -   amidines, such as acetamidine hydrochloride,    -   thioureas, urethanes, alcohols, polyols, amine oxides such as        N-methylmorpholine N-oxide, metal salts, sulfamides, carboxylic        acids and amino acids, nitrogenous heterocycles of the imidazole        or triazole family, such as imidazole hydrochloride.

Advantageously, the said denaturing agents are chosen from the family ofureas, guanidines, α-hydroxy acid or α-keto acid derivatives, mono-, di,tri- or polyhydroxylated aromatic derivatives, and cyclic or linearamides.

The term “urea”, which may be used as hair-relaxing active agent, meansany derivative comprising in its chemical formula a carbonyl groupsimply bonded to two nitrogen atoms. These ureas are more particularlyselected from the compounds of general formulae (I) and (II) below:

in which:

R1, R2, R3 and R4 represent, independently:

-   -   (i) a hydrogen atom or    -   (ii) a linear or branched C1-C4 lower alkyl or alkenyl radical,        optionally substituted with a radical chosen from: hydroxyl,        amino, dimethylamino, carboxyl or carboxamide or        N-methylcarboxamide,

when R1, R2 and R3 represent a hydrogen atom, R4 may also denote aradical chosen from: carboxamide; methoxy; ethoxy; 1,2,4-triazolyl;cyclopentyl; methoxy-carbonyl; ethoxycarbonyl; CO—CH═CH—COOH; phenyloptionally substituted with a chlorine atom or a hydroxyl radical;benzyl; or 2,5-dioxo-4-imidazolidinyl,

when R1 and R3 represent a hydrogen atom, R2 may also represent ahydrogen atom or a methyl or ethyl radical and R4 an acetyl radical,

when R1=R2=H, R3 and R4 may also form, with the nitrogen atom that bearsthem, a piperidine or 3-methylpyrazole or 3,5-dimethylpyrazole ormaleimide ring, and finally, R1 and R2 and also R3 and R4 may also form,with the nitrogen atom that bears them, an imidazole ring.

in which:

R5 and R6 represent, independently of each other:

-   -   (i) a hydrogen atom or    -   (ii) a linear or branched C1-C4 lower alkyl radical, optionally        substituted with a radical chosen from: hydroxyl, amino,        dimethylamino, carboxyl and carboxamide, and

A represents the radicals: CH2-CH2 or CH═CH or CH2-CO or CO—NH or CH═Nor CO—CO or CHOH—CHOH or (HOOC)CH—CH or CHOH—CO or CH2-CH2-CH2 orCH2-NH—CO or CH═C(CH3)-CO or NH—CO—NH or CH2-CH2-CO or CH2-N(CH3)-CH2 orNH—CH2-NH or CO—CH(CH3)-CH2 or CO—CH2-CO or CO—NH—CO or CO—CH(COOH)—CH2or CO—CH═C(COOH) or CO—CH═C(CH3) or CO—C(NH2)=CH or CO—C(CH3)=N orCO—CH═CH or CO—CH═N or CO—N═CH.

Among the compounds of formula (I), mention may be made especially ofthe following preferred compounds:

-   -   urea    -   methylurea    -   ethylurea    -   propylurea    -   isopropylurea    -   n-butylurea    -   sec-butylurea    -   isobutylurea    -   tert-butylurea    -   cyclopentylurea    -   1-ethoxyurea    -   2-hydroxyethylurea    -   N-(2-hydroxypropyl)urea    -   N-(3-hydroxypropyl)urea    -   N-(2-dimethylaminopropyl)urea    -   N-(3-dimethylaminopropyl)urea    -   1-(3-hydroxyphenyl)urea    -   benzylurea    -   N-carbamoylmaleimide    -   biuret    -   N-carbamoylmaleamic acid    -   1-piperidinecarboxamide    -   1,2,4-triazol-4-ylurea    -   hydantoic acid    -   methyl allophanate    -   ethyl allophanate    -   acetylurea    -   2-hydroxyethyleneurea    -   2-(hydroxyethyl)ethyleneurea    -   N-allyl-N′-ethylurea    -   diallylurea    -   2-chloroethylurea    -   N,N-dimethylurea    -   N,N-diethylurea    -   N,N-dipropylurea    -   1-cyclopentyl-1-methylurea    -   1,3-dimethylurea    -   1,3-diethylurea    -   1,3-bis(2-hydroxethyl)urea    -   1,3,bis(2-hydroxypropyl)urea    -   1,3-bis(3-hydroxypropyl)urea    -   1,3-dipropylurea    -   1-ethyl-3-propylurea    -   1-sec-butyl-3-methylylurea    -   1-isobutyl-3-methylurea    -   1-cyclopentyl-3-methylurea    -   N-acetyl-N′-methylurea    -   trimethylurea    -   1-butyl-3,3-dimethylurea    -   tetramethylurea    -   benzylurea.

Among the compounds of formula (II), mention may be made especially ofthe following preferred compounds:

-   -   parabanic acid    -   1,2-dihydro-3-H-1,2,4-triazol-2-one    -   barbituric acid    -   uracil    -   1-methyluracil    -   3-methyluracil    -   5-methyluracil    -   1,3-dimethyluracil    -   5-azauracil    -   6-azauracil    -   5-fluorouracil    -   6-fluorouracil    -   1,3-dimethyl-5-fluorouracil    -   5-aminouracil    -   6-aminouracil    -   6-amino-1-methyluracil    -   6-amino-1,3-dimethyluracil    -   4-chlorouracil    -   5-chlorouracil    -   5,6-dihydrouracil    -   5,6-dihydro-5-methyluracil    -   2-imidazolidione hydrate    -   1-methyl-2-imidazolidinone    -   1,3-dimethyl-2-imidazolidinone    -   4,5-dihydroxyimidazolidin-2-one    -   1-(2-hydroxyethyl)-2-imidazolidinone    -   1-(2-hydroxypropyl)-2-imidazolidinone    -   1-(3-hydroxypropyl)-2-imidazolidinone    -   4,5-dihydroxy-1,3-dimethylimidazolidin-2-one    -   1,3-bis(2-hydroxyethyl)-2-imidazolidinone    -   2-imidazolidone-4-carboxylic acid    -   1-(2-aminoethyl)-2-imidazole    -   4-methyl-1,2,4-triazoline-3,5-dione    -   2,4-dihydroxy-6-methylpyrimidine    -   1-amino-4,5-dihydro-1H-tetrazol-5-one    -   hydantoin    -   1-methylhydantoin    -   5-methylhydantoin    -   5,5-dimethylhydantoin    -   5-ethylhydrantoin    -   5-n-propylhydantoin    -   5-ethyl-5-methylhydantoin    -   5-hydroxy-5-methylhydantoin    -   5-hydroxymethylhydantoin    -   1-allylhydantoin    -   1-aminohydantoin    -   hydantoin 5-acetic acid    -   4-amino-1,2,4-triazolone-3,5-dione    -   hexahydro-1,2,4,5-tetrazine-3,6-dione    -   5-methyl-1,3,5-triazinon-2-one    -   1-methyltetrahydropyrimidin-2-one    -   2,4-dioxohexahydro-1,3,5-triazine    -   urazole    -   4-methylurazole    -   orotic acid    -   dihydroxyorotic acid    -   2,4,5-trihydroxypyrimidine    -   2-hydroxy-4-methylpyrimidine    -   4,5-diamino-2,6-dihydroxypyrimidine    -   barbituric acid    -   1,3-dimethylbarbituric acid    -   cyanuric acid    -   1-methylhexahydropyrimidine-2,4-dione    -   1,3-dimethyl-3,4,5,6-tetrahydro-2-1H-pyrimidinone    -   5-(hydroxymethyl-2,4-(1H,3H)-pyrimidinedione    -   2,4-dihydroxypyrimidine-5-carboxylic acid    -   6-azathymine    -   5-methyl-1,3,5-triazinan-2-one    -   N-carbamoylmaleamic acid    -   alloxane monohydrate.

Among the compounds of formula (I), mention may be made especially ofthe following particularly preferred compounds:

-   -   urea    -   methylurea    -   lurea    -   propylurea    -   1-ethoxyurea    -   2-hydroxyethylurea    -   N-(2-hydroxypropyl)urea    -   N-(3-hydroxypropyl)urea    -   N-(2-dimethylaminopropyl)urea    -   N-(3-dimethylaminopropyl)urea    -   1-(3-hydroxyphenyl)urea    -   N-carbamoylmaleimide    -   N-carbamoylmaleamic acid    -   1-piperidinecarboxamide    -   1,2,4-triazol-4-ylurea    -   hydantoic acid    -   acetylurea    -   2-hydroxyethyleneurea    -   2-(hydroxyethyl)ethyleneurea    -   N-allyl-N′-ethylurea    -   diallylurea    -   2-chloroethylurea    -   N,N-dimethylurea    -   1,3-dimethylurea    -   1,3-diethylurea    -   1,3-bis(2-hydroxyethyl)urea    -   1,3-dipropylurea    -   1-ethyl-3-propylurea    -   N-acetyl-N′-methylurea    -   benzylurea.

Among the compounds of formula (II) mention made be made especially ofthe following particularly preferred compounds:

-   -   1,2-dihdryo-3-H-1,2,4-traizol-2-one    -   uracil    -   1-methyl-2-imidazolidinone    -   1,3-dimethyl-2-imidazolidinone    -   4,5-dihydroxyimidazolidin-2-one    -   1-(2-hydroxyethyl)-2-imidazolidinone    -   4,5-dihydroxy-1,3-dimethylimidazolidin-2-one    -   1,3-bis(2-hydroxyethyl)-2-imidazolidinone    -   2-imidazolidone-4-carboxylic acid    -   1-(2-aminoethyl)-2-imidazole    -   hydantoin    -   5-hydroxymethylhydantoin    -   hydantoin 5-acetic acid    -   urazole    -   orotic acid    -   dihydroxyorotic acid    -   2,4,5-trihydroxypyrimidine    -   4,5-diamino-2,6-dihydroxypyrimidine    -   2,4-dihydroxypyrimidine-5-carboxylic acid    -   5-methyl-1,3,5-triazinan-2-one    -   1,3-dimethyl-3,4,5,6-tetrahydro-2-1H-pyrimidinone    -   N-carbamoylmaleamic acid    -   alloxane monohydrate.

The term “guanidine”, which may be used as relaxing active agent, meansany derivative comprising in its chemical formula at least one carbonatom doubly bonded to a nitrogen atom and singly bonded to two othernitrogen atoms. These guanidines are more particularly selected from thecompounds of general formula (III) below:

in which

R1, R2, R3, R4 and R5 represent, independently:

-   -   (iii) a hydrogen atom or    -   (iv) a linear or branched C1-C4 lower alkyl or alkenyl radical,        optionally substituted with one or two radicals chosen from:        hydroxyl, amino, dimethylamino, methoxy, ethoxy, carboxyl,        carboxamide, N-methylcarboxamide or SO₃H,    -   when R1, R2 and R3 and R4 represent a hydrogen atom, R5 may also        denote a radical chosen from the following: acetyl;        chloroacetyl; carboxamide; methoxy; ethoxy; 1,2,4-triazolyl;        cyclopentyl; methoxycarbonyl; ethoxycarbonyl; CO—CH═CH—COOH;        phenyl optionally substituted with a chlorine atom or a hydroxyl        radical; benzyl; thiazolidone; benzimidazole; benzoxazole;        benzothiazole; or C(═NH)—NR6R7 in which R6 and R7 denote,        independently of each other, a hydrogen atom or a linear or        branched C1-C4 lower alkyl radical, optionally substituted with        one or two radicals chosen from: hydroxyl, amino, dimethylamino,        carboxyl or carboxamide; or N-methylcarboxamide; or        alternatively a phenyl radical,    -   when R1=R2=R3=H, R4 and R5 may also form, with the nitrogen atom        that bears them, a pyrrolidine, piperidine, pyrazole or        1,2,4-triazole ring optionally substituted with one or two        radicals chosen from: hydroxyl, amino or carboxyl,    -   when R1=R2=H and R4=H or methyl, R3 and R5 may also together        form a 5-membered ring optionally containing an oxo group,    -   and the organic or mineral salts thereof.

Among the compounds of formula (III), mention may be made especially ofthe following preferred compounds:

-   -   guanidine hydrochloride    -   guanidine acetate    -   guanidine sulfate    -   guanidine carbonate    -   guanidine bicarbonate    -   guanidine phosphate    -   guanidine sulfamate    -   aminoguanidine    -   aminoguanidine hydrochloride    -   aminoguanidine sulfate    -   aminoguanidine bicarbonate    -   1,3-diaminoguanidine hydrochloride    -   1-acetylguanidine    -   chloroacetylguanidine hydrochloride    -   guanylurea    -   guanylurea phosphate    -   phenylguanidine carbonate    -   phenylguanidine bicarbonate    -   1-methylguanidine hydrochloride    -   1,1-dimethylguanidine hydrochloride    -   1-ethylguanidine hydrochloride    -   1,1-diethylguanidine hydrochloride    -   creatine    -   creatine monohydrate    -   creatinine hydrochloride    -   agmatine    -   agmatine sulfate    -   guanidinoacetic acid    -   guanidinosuccinic acid    -   3-guanidinopropionic acid    -   4-guanidinobutyric acid    -   5-guanidinovaleric acid    -   β-N-methylguanidinopropionic acid    -   N-methylguanidinopropionic acid    -   N-(2-hydroxyethyl)guanidine    -   N-(3-hydroxypropyl)guanidine    -   biguanide hydrochloride    -   N-methylbiguanide hydrochloride    -   N-ethylbiguanide hydrochloride    -   N-propylbiguanide hydrochloride    -   N-butylbiguanide hydrochloride    -   N-butylbiguanide hydrochloride    -   1,1-dimethylbiguanide hydrochloride    -   1-phenylbiguanide    -   1,1,3,3-tetramethylguanidine hydrochloride    -   1-phenylbiguanide    -   1,1,3,3-tetramethylguanidine hydrochloride    -   2-tert-butyl-1,1,3,3-tetramethylguanidine hydrochloride    -   L-arginine    -   D-arginine    -   DL-arginine    -   arginic acid    -   N-amidino-N-(2,3-dihydroxypropyl)glycine    -   N-amidinotaurine    -   2-imino-2-imidazolidineacetic acid    -   1-(2,2-diethoxyethyl)guanidine    -   1H-pyrazole-1-carboxamidine hydrochloride    -   5-hydroxy-3-methyl-1H-pyrazole-1-carbox-imidamide    -   3,5-diamino-1H-1,2,4-triazole-1-carboximidamide hydrochloride    -   2-guanidone-4-thiazolidone    -   2-guanidinobenzimidazole    -   2-guanidinobenzoxazole    -   2-guanidinobenzothiazole    -   pyrrolidinoformamidine hydrochloride.

Among the compounds of formula (III), mention may be made especially ofthe following particularly preferred compounds:

-   -   guanidine hydrochloride    -   guanidine acetate    -   guanidine sulfate    -   guanidine carbonate    -   guanidine bicarbonate    -   guanidine phosphate    -   guanidine sulfamate    -   aminoguanidine hydrochloride    -   aminoguanidine sulfate    -   aminoguanidine bicarbonate    -   1,3-diaminoguanidine hydrochloride    -   guanylurea phosphate    -   1-methylguanidine hydrochloride    -   1,1-dimethylguanidine hydrochloride    -   1-ethylguanidine hydrochloride    -   creatine monohydrate    -   creatinine hydrochloride    -   agmatine    -   agmatine sulfate    -   guanidinoacetic acid    -   guanidinosuccinic acid    -   3-guanidinopropionic acid    -   β-N-methylguanidinopropionic acid    -   N-methylguanidinopropionic acid    -   N-(2-hydroxyethyl)guanidine    -   N-(3-hydroxypropyl)guanidine    -   biguanide hydrochloride    -   N-methylbiguanide hydrochloride    -   N-ethylbiguanide hydrochloride    -   1,1-dimethylbiguanide hydrochloride    -   1,1,3,3-tetramethylguanidine hydrochloride    -   2-tert-butyl-1,1,3,3-tetramethylguanidine hydrochloride    -   L-arginine    -   DL-arginine    -   arginic acid    -   N-amidino-N-(2,3-dihydroxypropyl)glycine    -   N-amidinotaurine    -   2-imino-1-imidazolidineacetic acid    -   1H-pyrazole-1-carboxamidine hydrochloride    -   3,5-diamino-1H-1,2,4-triazole-1-carboximidamide hydrochloride    -   2-guanidone-4-thiazolidone.

The term “α-hydroxy acid and α-keto acid derivatives”, which may be usedas hair-relaxing active agent, means any derivative selected from thecompounds of general formulae (IV) and (V) below:

R1 represents H, OH, NH2, CH2-COOH or a linear or branched C1-C4 alkylradical,

R2 represents H, COOH, CHOH—COOH, CF3, CH═CH2, NHCONH2, a linear,branched or cyclic C1-C8 alkyl radical optionally substituted with aradical chosen from OH, C1, NH2, COOH, CF3 and SCH3; or a phenyl orbenzyl radical optionally substituted with one OH or OCH3 radical;

or alternatively the radical

R1 and R2 may also together form an oxo radical (═O) or a cyclopropyl,cyclobutyl, hydroxycyclobutyl, cyclo-pentyl or cyclohexyl ring with thecarbon atom that bears them, or alternatively a radical

when R1=H, R2 may also represent a (CHOH)2CH2OH or (CHOH)3CH2OH radical,

R represents OH or NR3R4 with R3, R4=H or a linear or branched C1-C4alkyl radical optionally substituted with one or two OH radicals

and the stereoisomers, organic or mineral salts and solvates thereof.

Preferred compounds of formula (IV) that may be mentioned include:

glycolic acid

oxalic acid

lactic acid

1-hydroxy-1-cyclopropanecarboxylic acid

2-hydroxy-3-butenoic acid

2-hydroxyisobutyric acid

2-hydroxy-n-butyric acid

isoserine

glyceric acid

2-hydroxy-3-methylbutyric acid

2-hydroxy-2-methylbutyric acid

2-hydroxyvaleric acid

4-amino-2-hydroxybutyric acid

1-hydroxycyclohexanecarboxylic acid

dihydroxyfumaric acid

citramalic acid

tartaric acid

citric acid

2-hydroxy-4-(methylthio)butyric acid

mandelic acid

2-hydroxy-3-methylvaleric acid

glyoxylurea

β-imidazolelactic acid

2-trifluoromethyl-2-hydroxypropionic acid

hexahydromandelic acid

2-hydroxyoctanoic acid

arabic acid

3-phenylactic acid

hydroxyphenylglycine

3-hydroxymandelic acid

4-hydroxymandelic acid

2-hydroxynonanoic acid

L-arginic acid

3-methoxymandelic acid

4-methoxymandelic acid

3-(4-hydroxyphenyl)lactic acid

tartronic acid

tartaric acid

β-chlorolactic acid

1-cylcopentanol-1-carboxylic acid

1,2-dihydroxycyclobutanecarboxylic acid

2-ethyl-2-hydroxybutric acid

α-hydroxyisocaproic acid

α-hydroxycaproic acid

2-hydroxy-3,3-dimethylbutyric acid

malic acid

hydroxytartronic acid

gluconic acid

lactamide

-   -   N-methyllactamide

N-ethyllactamide

N,N-dimethyllactamide

N-2-hydroxyethyllactamide

and the stereoisomers, organic or mineral salts and solvates thereof.

The compounds of formula (IV) that are particularly preferred are chosenfrom:

glycolic acid

oxalic acid

L-lactic acid

DL-lactic acid

D-lactic acid

malic acid

tartaric acid

DL-glyceric acid

arabic acid

gluconic acid

hydroxytartronic acid

lactamide

N-methyllactamide

N-ethyllactamide

N-2-hydroxyethyllactamide

Definition of the α-keto acid derivatives of general formula (V):

R5 represents H, COOH, a linear or branched C1-C6 alkyl radicaloptionally substituted with an OH, COOH or Br radical; a phenyl orbenzyl radical optionally substituted with an OH or COOH radical; or anindolyl radical or

and the stereoisomers, organic or mineral salts and solvates thereof.

The preferred compounds of formula (V) are chosen from:

pyruvic acid

2-ketobutyric acid

β-hydroxypyruvic acid

3-methyl-2-oxobutyric acid

2-oxovaleric acid

ketomalonic acid

3-methyl-2-oxovaleric acid

trimethylpyruvic acid

oxoacetic acid

2-ketoglutaric acid

benzylformic acid

2-oxooctanoic acid

2-oxoadipic acid

phenylpyruvic acid

bromopyruvic acid

2-ketopimelic acid

4-hydroxyphenylpyruvic acid

3-indoleglyoxalic acid

imidazolopyruvic acid HCl

2-keto-L-gulonic acid

2-carboxy-α-oxobenzeneacetic acid

3-indolepyruvic acid

2-ketoglutaric acid dihydrate

pyruvamide

N-methylpyruvamide

N-ethylpyruvamide

N,N-dimethylpyruvamide

N-2-hydroxyethylpyruvamide

and the stereoisomers, organic or mineral salts and solvates thereof.

The compounds of formula (V) that are particularly preferred are chosenfrom:

pyruvic acid

2-ketobutyric acid

β-hydroxypyruvic acid

ketomalonic acid

oxoacetic acid

2-ketoglutaric acid

2-keto-L-gulonic acid

2-ketoglutaric acid dihydrate

pyruvamide

and the stereoisomers, organic or mineral salts and solvates thereof.

The term “polyhydroxylated aromatic derivatives”, which may be used ashair-relaxing active agent, means any derivative selected from thecompounds of general formula (VI) below:

in which:

-   -   R1, R2, R3 and R4 represent, independently of each other:    -   H, F, Cl, Br, OH, OCH₃, OEt, CHO, COCH₃, COOH, CH₂NH₂,        CH₂CH₂NH₂, CH₂OH, CH₂CH₂OH, CH₂COCH₃, CH₂COOH, CH₂CH₂COOH,        CH₂CONH₂, CHOH—CH₂OH, —CH(NH₂) COOH, NHCOCH₃, COCH₂CH₃, CONH₂    -   or alternatively a linear or branched C1-C5 alkyl radical

when the two OH radicals are in a meta position and

when R1, R2 and R3 represent a hydrogen atom, R4 may also represent NH₂,

and the stereoisomers, organic or mineral salts and solvates thereof.

The preferred compounds of formula (VI) are chosen from:

catechol

resorcinol

4-methylcatechol

3-methylcatechol

2-methylresorcinol

5-methylresorcinol

4-methylresorcinol

pyrogallol

1,2,4-trihydroxybenzene

phloroglucinol

3-fluorocatechol

4-fluorocatechol

4-fluororesorcinol

2,3-dihydroxybenzaldehyde

3,4-dihydroxybenzaldehyde

2,4-dihydroxybenzaldehyde

3,5-dihydroxybenzaldehyde

4-ethylcatechol

4-ethylresorcinol

2,5-dimethylresorcinol

4,5-dimethylresorcinol

2,4-dimethyl-1,3-benzenediol

3,4-dihydroxybenzylamine

3,5-dihydroxybenzylamine

3-methoxycatechol

5-methylpyrogallol

3,4-dihydroxybenzyl alcohol

5-methoxyresorcinol

2,4,6-trihydroxytoluene

3,5-dihydroxybenzyl alcohol

2-methoxyresorcinol

5-methylpyrogallol

4-methoxyresorcinol

3,5-dihydroxytoluene monohydrate

4-chlorocatechol

3-chlorocatechol

4-chlororesorcinol

2-chlororesorcinol

3′,4′-dihydroxyacetophenone

2′,3′-dihydroxyacetophenone

2′,6′-dihydroxyacetophenone

2′,4′-dihydroxyacetophenone

3′,5′-dihydroxyacetophenone

2,6-dihydroxy-4-methylbenzaldehyde

3-isopropylcatechol

4-isopropylcatechol

4-propylresorcinol

2,4-dihydroxy-1,3,5-trimethylbenzene

3,4-dihydroxybenzamide

3,5-dihydroxybenzamide

2,6-dihydroxybenzamide

2,4-dihydroxybenzamide

3-hydroxytyramine

2,3-dihydroxybenzoic acid

3,4-dihydroxybenzoic acid

2,4-dihydroxybenzoic acid

2,6-dihydroxybenzoic acid

3,5-dihydroxybenzoic acid

2,3,4-trihydroxybenzaldehyde

2,4,6-trihydroxybenzaldehyde

3,4,5-trihydroxybenzaldehyde

2,4,5-trihydroxybenzaldehyde

2-(3,4-dihydroxyphenyl)ethanol

2,4,6-trihydroxy-1,3-dimethylbenzene

2,6-dihydroxy-4-methylbenzyl alcohol

2-fluoro-3,4-dihydroxybenzaldehyde

3,4-dihydroxy-6-fluorobenzaldehyde

2-methoxyphloroglucinol

3,5-dihydroxyanisole hydrate

4-aminoresorcinol hydrochloride

2-aminoresorcinol hydrochloride

5-aminobenzene-1,3-diol hydrochloride

phloroglucinol dihydrate

3′,4′-dihydroxypropiophenone

3,4-dihydroxyphenylacetone

(2,3-dihydroxyphenyl)acetone

2′,4′-dihydroxypropiophenone

2′,4′-dihydroxy-3′-methylacetophenone

(2,4-dihydroxyphenyl)acetone

(3,5-dihydroxyphenyl)acetone

2,6-dihydroxy-4′-methylacetophenone

4-tert-butylcatechol

4-N-butylresorcinol

2,4-diethyl-1,3-benzenediol

3,4-dihydroxyphenylacetamide

3-hydroxyacetaminophen

2′,3′,4′-trihydroxyacetophenone

3,4-dihydroxyphenylacetic acid

2,3-dihydroxy-4-methoxybenzaldehyde

3,4-dihydroxy-5-methoxybenzaldehyde

2′,3′,4′-trihydroxyacetophenone

2′,4′,6′-trihydroxyacetophenone

3,5-dihydroxy-4-methylbenzoic acid

2,6-dihydroxy-4-methylbenzoic acid

2,4-dihydroxy-6-methylbenzoic acid

3,5-dihydroxyphenylacetic acid

2-ethyl-5-methoxybenzene-1,3-diol

3,4,5,-trihydroxybenzamide

4-amino-3,5-dihydroxybenzoic acid

2,3,4-trihydroxybenzoic acid

2,3,4-trihydroxybenzoic acid

gallic acid

2,4,6-trihydroxybenzoic acid

3,4-dihydroxyphenyl glycol

1,2-dihydroxy-4,5-dimethoxybenzene

3,5-dihydroxyacetophenone monohydrate

3,4-dihydroxybenzoic acid monohydrate

3,4,5-trihydroxybenzaldehyde

hexahydroxybenzene

3,5-dihydroxybenzylamine hydrochloride

4,6-diaminoresorcinol hydrochloride

4,5-dichlorocatechol

3,5-dichlorocatechol

4,6-dichlororesorcinol

2′,4′-dihydroxy-3′-methylpropiophenone

1-(3-ethyl-2,6-dihydroxyphenyl)ethan-1-one

3-(3,4-dihydroxyphenyl)propionic acid

(2,3,4-trihydroxyphenyl)acetone

(2,4,5-trihydroxyphenyl)acetone

(3,4,5-trihydroxyphenyl)acetone

2′,6′-dihydroxy-4′-methoxyacetophenone

1-(2,6-dihydroxy-3-methoxyphenyl)ethan-1-one

3(2,4-dihydroxyphenylpropionic acid

2,4-dihydroxy-3,6-dimethylbenzoic acid

(2,3,4-trihydroxyphenyl)acetone

(2,4,5-trihydroxyphenyl)acetone

(2,4,6-trihydroxyphenyl)acetone

(3,4,5-trihydroxyphenyl)acetone

3,4-dihydroxymandelic acid

5-hydroxyisovanillic acid

3,4,5-trihydroxybenzamide hydrate

4-bromocatechol

and the stereoisomers, organic or mineral salts and solvates thereof.

The compounds of formula (VI) that are particularly preferred are chosenfrom:

resorcinol

2-methylresorcinol

5-methylresorcinol

4-methylresorcinol

pyrogallol

1,2,4-trihydroxybenzene

4-ethylresorcinol

2,5-dimethylresorcinol

4,5-dimethylresorcinol

2,4-dimethyl-1,3-benzenediol

3,4-dihydroxybenzylamine

3,5-dihydroxybenzylamine

5-methylpyrogallol

3,4-dihydroxybenzyl alcohol

5-methoxyresorcinol

2,4,6-trihydroxytoluene

3,5-dihydroxybenzyl alcohol

2-methoxyresorcinol

5-methylpyrogallol

4-methoxyresorcinol

3,5-dihydroxytoluene monohydrate

4-propylresorcinol

2,4-dihydroxy-1,3,5-trimethylbenzene

3,4-dihydroxybenzamide

3,5-dihydroxybenzamide

2,6-dihydroxybenzamide

2,4-dihydroxybenzamide

3-hydroxytyramine

2,3-dihydroxybenzoic acid

3,4-dihydroxybenzoic acid

2,6-dihydroxybenzoic acid

3,5-dihydroxybenzoic acid

2-(3,4-dihydroxyphenyl)ethanol

2,4,6-trihydroxy-1,3-dimethylbenzene

2,6-dihydroxy-4-methylbenzyl alcohol

2-methoxyphloroglucinol

3,5-dihydroxyanisole hydrate

4-aminoresorcinol hydrochloride

2-aminoresorcinol hydrochloride

5-aminobenzene-1,3-diol hydrochloride

phloroglucinol dihydrate

2,4-diethyl-1,3-benzenediol

3,4-dihydroxyphenylacetamide

3,4-dihydroxyphenylacetic acid

3,5-dihydroxy-4-methylbenzoic acid

2,6-dihydroxy-4-methylbenzoic acid

2,4-dihydroxy-6-methylbenzoic acid

3,5-dihydroxyphenylacetic acid

2-ethyl-5-methoxybenzene-1,3-diol

3,4,5-trihydroxybenzamide

4-amino-3,5-dihydroxybenzoic acid

3,4-trihydroxybenzoic acid

gallic acid

2,4,6-trihydroxybenzoic acid

DL-3,4-dihydroxyphenyl glycol

1,2-dihydroxy-4,5-dimethoxybenzene

3,4-dihydroxybenzoic acid monohydrate

hexahydroxybenzene

3,5-dihydroxybenzylamine hydrochloride

sodium γ-resorcylate

sodium β-resorcylate

4,6-diaminoresorcinol hydrochloride

3-(3,4-dihydroxyphenyl)propionic acid

2,4-dihydroxy-3,6-dimethylbenzoic acid

DL-3,4-dihydroxymandelic acid

hydroxyisovanillic acid

3,4,5-trihydroxybenzamide acid hydrate

gallic acid monohydrate

and the stereoisomers, organic or mineral salts and solvates thereof.

The term “cyclic and linear amide derivatives” which may be used ashair-relaxing active agent, means any derivative selected from thecompounds of general formulae (VII) and (VIII) below:

with

X=0 to 3

R1, R2, R3, R4, R5 and R6, which may be identical or different, possiblytaking the following meaning:

-   -   H,    -   F,    -   linear or branched C1-C30 alkyl, possibly comprising one or more        unsaturations,        -   optionally interrupted with —O—, —S—, —NR7-, —C(O)—,            —OC(O)—, —C(O)O—, —C(O)NR7-, —NR7C(O)—, —OC(O)NR7-,            —NR7C(O)O—, —NR7C(O)NR8-, —NR7SO2-, —NR7SO2NR8-, —SO2NR7-,            —OSO2-, —C(S)NR7-, —NR7C(S)—,        -   optionally substituted with —OR7, —SR7, —NR7R8, —C(O)R7,            —OC(O)R7, —C(O)OR7, —C(O)NR7R8, —NR7C(O)R8, —OC(O)NR7R8,            —NR7C(O)OR8, —NR7C(O)NR8R9, —NR7SO2R8, —NR7SO2NR8R9,            —SO2NR7R8, —OSO2R7, —C(S)NR7R8, —NR7C(S)R8, an aromatic or            non-aromatic, heterocyclic or non-heterocyclic ring,            possibly containing 3 to 10 atoms,    -   —OR7, —SR7, —NR7R8, —C(O)R7, —OC(O)R7, —C(O)OR7, —C(O)NR7R8,        —NR7C(O)R8, —OC(O)NR7R8, —NR7C(O)OR8, —NR7C(O)NR8R9, —NR7SO2R8,        —NR7SO2NR8R9, —SO2NR7R8, —C(S)NR7R8, —NR7C(S) R8,    -   an aromatic or non-aromatic, heterocyclic or non-heterocyclic        ring, possibly containing 3 to 10 carbon atoms, which is        optionally substituted,    -   R1, R2, R3, R4, R5 and R6 possibly forming in pairs, with the        carbon atoms to which they are attached, a (hetero)cycle of 3 to        7 atoms, optionally interrupted with O, S, N, —C(O)—, —C(O)O—,        —C(O)NR7-,    -   R1R2, R3R4, and R5R6 possibly being combined in pairs to form an        oxo function,

R7, R8 and R9, which may be identical or different, possibly taking thefollowing meaning:

-   -   H, F, optionally substituted linear or branched C1-C30 alkyl,        possibly containing one or more unsaturations,    -   one of the 20 natural N-branched amino acids, C-protected with        standard protecting groups or one of the 20 natural C-branched        amino acids, N-protected with standard protecting groups,    -   an aromatic or non-aromatic, heterocyclic or non-heterocyclic        ring, possibly containing 3 to 10 atoms,

and also the stereoisomers, organic or mineral salts and solvatesthereof.

The preferred compounds of formula (VII) are chosen from:

2-pyrrolidone

3-methyl-2-pyrrolidone

pyroglutamic acid

5-methyl-2-pyrrolidone

succinimide

α-methyl-α-phenylsuccinimide

ethyl pyroglutamate

2-oxo-4-phenylpyrrolidine-3-carboxylic acid

pyrrolidonyl-4-butyramide

5-(hydroxymethyl)-2-pyrrolidinone

methyl pyroglutamate

ethyl 2-oxo-4-phenyl-3-pyrrolidinecarboxylate

4-(hydroxy)-4-methylpyrrolidin-2-one

4-fluoro-5-pyrrolidone-2-carboxylic acid

4,4-pentamethylene-2-pyrrolidinone

[(5-oxopyrrolidine-2-carbonyl)amino]acetic acid

2-[(5-oxopyrrolidine-2-carbonyl)amino]-3-phenylpropionic acid

5-methoxy-2-pyrrolidinone

2-azabicyclo[2.2.1]hept-5-en-3-one

butyl 2-pyrrolidone-5-carboxylate

octyl 2-pyrrolidone-5-carboxylate

4-carbamoyl-2-[(5-oxopyrrolidin-2-carbonyl)amino]-butyric acid

4-hydroxy-2-pyrrolidinone

2-dimethylamino ethyl 5-oxopyrrolidine-2-carboxylate

3-(1H-indol-3-yl)-2-[(5-oxopyrrolidin-2-carbonyl)-amino]propionic acid

5-pyridin-3-ylpyrrolidin-2-one

2-azabicyclo[2.2.1]heptan-3-one

methyl 2-[3-(methoxymethyl)-5-oxo-2-pyrrolidinyl]-acetate

4-phenyl-2-pyrrolidinone

4-spiro-[3[(2-pyrrolidonone)]piperidine

(4-[3-(cyclopentyloxy)-4-methoxyphenyl]pyrrolidin-2-one

2-amino-5-oxo-5-(5-oxopyrrolidin-2-yl)pentanoic acid

2-(2,5-dioxopyrrolidin-3-ylsulfanyl)nicotinic acid

3-hydroxynorcotinine

3-benzyl-5-hydroxymethylpyrrolin-2-one

ethyl 4-methylpyroglutamate

ethyl 4-ethylpyroglutamate

ethyl 4-isopropylpyroglutamate

ethyl 4-benzylpyroglutamate

3-ethyl-5-hydroxymethylpyrrolidin-2-one

5-hydroxymethyl-3-methylpyrrolidin-2-one

5-oxopyrrolidine-3-carboxylic acid

5-hydroxymethyl-3-isopropylpyrrolidin-2-one

5-hydroxymethylpyrrolidin-2-one

5-aminomethylpyrrolidin-2-one

ethyl 2-oxopyrrolidine-3-carboxylate

3-hydroxypyrrolidin-2-one

3-ethyl-4-methylpyrroline-2-one

3,4-(1,3-propanediyl)-2-pyrrolidinone

8-valerolactam

3-carbethoxy-2-piperidone glutarimide

3,3-dimethylglutarimide

3-ethyl-3-methylglutarimide

6-methyl-2-piperidone

3-methylpiperidin-2-one

D-mannono-D-lactam

N-(2-aminoethyl)-2-oxopiperidine-3-carboxamide

4-phenyl-δ-valerolactam

3-amino-4-phenyl-δ-valerolactam

4-methyl-3-phenyl-δ-valerolactam

3-methyl-5-phenyl-δ-valerolactam

3-(2-isopropoxycarbonylethyl)-6-oxopiperidine-3-carboxylic acid

3-(2-benzylcarbamoylethyl)-6-oxopioperidine-3-carboxylic acid

methyl-2-oxopiperidine-3-carboxylate

3,4,5-trihydroxy-6-oxo-2-piperidinecarboxylic acid

2-piperidinone-6-carboxylic acid

5-hydroxypiperidin-2-one

ethyl 5-methyl-2-oxo-3-piperidinecarboxylate

6-oxopiperidine-2-carboxylic acid

4-hydroxypiperidin-2-one

2-azetidinone

ε-caprolactam

and the stereoisomers, organic or mineral salts and/or solvates thereof.

The compounds of formula (VII) that are particularly preferred arechosen from:

2-pyrrolidone

pyroglutamic acid

3-methyl-2-pyrrolidone

5-methyl-2-pyrrolidone

5-(hydroxymethyl)-2-pyrrolidinone

5-oxopyrrolidine-3-carboxylic acid

5-aminomethylpyrrolidin-2-one

4-hydroxy-2-pyrrolidinone

and the stereoisomers, organic or mineral salts and/or solvates thereof.

Definition of the linear amides of general formula (VIII)

with

X=0 or 1

R1 possibly taking the following meaning:

-   -   linear or branched C1-C30 alkylene, possibly containing one or        more unsaturations,        -   optionally interrupted with —O—, —S—, —NR7-, —C(O)—,            —OC(O)—, —C(O)O—, —C(O)NR7-, —NR7C(O)—, —OC(O)NR7-,            —NR7C(O)O—, —NR7C(O)NR8-, —NR7SO2-, —NR7SO2NR8-, —SO2NR7-,            —OSO2-, —C(S)NR7-, —NR7C(S)—,        -   optionally substituted with:            -   F, Cl            -   —OR7, —SR7, —NR7R8, —C(O)R7, —OC(O)R7, —C(O)OR7,                —C(O)NR7R8, —NR7C(O)R8, —OC(O)NR7R8, —NR7C(O)OR8,                —NR7C(O)NR8R9, —NR7SO2R8, —NR7SO2NR8R9, —SO2NR7R8,                —OSO2R7, —C(S)NR7R8, —NR7C(S)R8,            -   an aromatic or non-aromatic, heterocyclic or                non-heterocyclic ring, possibly containing 3 to 10                atoms, with the exception of hydroxyl or oxo                substituents in a position alpha to the amide function

R2 possibly taking the following meaning:

-   -   H    -   F, Cl    -   an aromatic or non-aromatic, heterocyclic or non-heterocyclic        ring, which is optionally substituted, possibly containing 3 to        10 atoms,    -   —OR7, —SR7, —NR7R8, —C(O)R7, —OC(O)R7, —C(O)OR7, —C(O)NR7R8,        —NR7C(O)R8, —OC(O)NR7R8, —NR7C(O)OR8, —NR7C(O)NR8R9, —NR7SO2R8,        —NR7SO2NR8R9, —SO2NR7R8, —C(S)NR7R8, —NR7C(S)R8

R3 possibly taking the following meaning:

-   -   H    -   linear or branched C1-C30 alkyl, possibly containing one or more        unsaturations,        -   optionally interrupted with —O—, —S—, —NR7-, —C(O)—,            —OC(O)—, —C(O)O—, —C(O)NR7-, —NR7C(O)—, —OC(O)NR7-,            —NR7C(O)O—, —NR7C(O)NR8-, —NR7SO2-, —NR7SO2NR8-, —SO2NR7-,            —OSO2-, —C(S)NR7-, —NR7C(S)—,        -   optionally substituted with:            -   F, Cl            -   —OR7, —SR7, —NR7R8, —C(O)R7, —OC(O)R7, —C(O)OR7,                —C(O)NR7R8, —NR7C(O)R8, —OC(O)NR7R8, —NR7C(O)OR8,                —NR7C(O)NR8R9, —NR7SO2R8, —NR7SO2NR8R9, —SO2NR7R8,                —OSO2R7, —C(S)NR7R8, —NR7C(S)R8        -   an aromatic or non-aromatic, heterocyclic or            non-heterocyclic ring, possibly containing 3 to 10 atoms,

R7, R8 and R9, which may be identical or different, possibly taking thefollowing meaning:

-   -   H,    -   linear or branched C1-C30 alkyl, possibly containing one or more        unsaturations,    -   one of the 20 natural N-branched amino acids, C-protected with        standard protecting groups, or one of the 20 natural C-branched        amino acids, N-protected with standard protecting groups,    -   an aromatic or non-aromatic, heterocyclic or non-heterocyclic        ring, possibly containing 3 to 10 atoms,

and also the stereoisomers thereof and the organic or mineral salts andsolvates thereof.

The preferred compounds of formula (VIII) are chosen from:

acetamide

N-methylacetamide

propionamide

N-ethylacetamide

N-methylpropionamide

N-butyramide

N-(hydroxymethyl)acetamide

methoxyacetamide

hydracrylamide

2-mercaptoacetamide

acetoacetamide

N-(N-propyl)acetamide

N-ethylpropionamide

valeramide

malonamide

N-acetylethylenediamine

2-amino-N-ethylacetamide

N-acetylethanolamine

3-chloropropionamide

glycinamide

N-(cyclopropylmethyl)acetamide

N-methylacetoacetamide

1-acetamidoacetone

N-methylvaleramide

N-butylacetamide

hexanamide

N-acetylglycinamide

succinamide

N-ethyl-2-methylaminoacetamide

N-acetylglycine

succinamic acid

methylcarbamoylacetate

N-(2-hydroxyethyl)propionamide

N1-(3-hydroxypropyl)acetamide

5-hydroxyvaleramide

3-amino-3-thioxopropanamide

O-(2-hydroxyethyl)glycolamide

3,4-dihydroxybutyramide

N-(2-chloroethyl)acetamide

N-(3-methylbutyl)acetamide

N-methylsuccinamic acid

ethyl carbamoylacetate

glycylglycine

asparagine

2-amino-N-(2-methoxyethyl)acetamide

2-(2-amino-2-oxoethoxy)acetic acid

2-phenylacetamide

pyridine-2-acetamide

pyridine-4-acetamide

methylsulfonylacetamide

4-aminobutyramide

5-acetaminomethyltetrazole

thiphene-2-acetamide

4-thiazoleacetamide

1-aminocyclopentanacetamide

2-piperazin-1-ylacetamide

N-octanamide

N,N′-diacetylethylenediamine

adipamide

2-morpholinoacetamide

ethyl acetamidoacetate

4-acetamidbutyric acid

2-(acetylamino)ethyl acetate

N-(2-hydroxyethyl)acetoacetamide

isopropyl carbamoylacetate

2-amino-N-methylsuccinamic acid

glutamine

N-(2-methoxyethyl)-2-methylaminoacetamide

N-methyl-2-phenylacetamide

N-benzylacetamide

N-propylpyrrolidine-2-carboxamide

N-(tert-butyl)-1,2,3,4-tetrahydroisoquinoline-2-carbox-amide

N,N-butylpropionamide

N-1,3,3-trimethylbutanamide

N-α-acetyl-L-lysine-N-methylamide

L-proline N-octylamide

and also the stereoisomers thereof and the organic or mineral salts andsolvates thereof,

and also the following amino acids and derivatives:

AC-ALA-NHME

AC-β-ALA-OH

AC-β-ALA-OME

AC-GLY-NHME

AC-HIS-NHME

AC-ILE-NHME

AC-LEU-GLY-OH

AC-LEU-NHME

AC-LYS-NHME

AC-PHE-NHME

AC-SER-GLY-OH

AC-VAL-NHME

H-β-ALA-GLY-OH

H-β-ALA-NH2

H-GLY-ALA-OH

H-GLY-NHME

H-PRO-ALA-OH

H-PRO-ALA-OH

H-PRO-β-ALA-OH

H-PRO-GLY-NH2

H-PRO-GLY-OH

H-PRO-GLY-OH

H-PRO-ILE-OH

H-PRO-LEU-OH

H-PRO-NHCH3

H-PRO-NHET

H-PRO-SER-OH

H-PRO-VAL-OH

H-PRO-VAL-OH

SAR-GLY-OH

SAR-NH2

and also the stereoisomers thereof and the organic or mineral salts andsolvates thereof.

The compounds of formula (VIII) that are particularly preferred arechosen from:

glycineamide

acetamide

N-methylacetamide

N-ethylacetamide

propionamide

N-ethylpropionamide

and also the stereoisomers thereof and the organic or mineral salts andsolvates thereof.

In the compositions according to the invention intended for a process ofrelaxing, uncurling or straightening the hair, the mixture in anyproportion of at least two denaturing agents as defined previously isadvantageously present in an overall molar concentration of between 1 Mand 8 M and more advantageously in a concentration of between 2 M and 8M.

In the process according to the invention and in the kit, the pH of thecompositions is preferably less than 9 and more preferentially less than7.

The compositions according to the invention are either in the form of anaqueous solution or in the form of a thickened cream so as to keep thehair as straight as possible. These creams are prepared in the form of“heavy” emulsions.

For the purpose of improving the cosmetic properties of keratin fibresor to attenuate or avoid their degradation, the composition usedaccording to the invention may also comprise one or more additionalcosmetic active agents. Generally, the said additional cosmetic activeagent(s) represent(s) from 0.01% to 30% and preferably from 0.1% to 10%by weight relative to the total weight of the cosmetic composition.

Generally, the composition applied to the keratin fibres is applied inan amount of from 0.05 to 20 g and preferably from 0.1 to 10 g ofcomposition per gram of dry keratin fibre.

After applying the composition, and before raising the temperature ofthe keratin fibres using a heating means, the said composition may beleft to act, generally for 30 seconds to 60 minutes and preferably 5 to45 minutes.

The process according to the invention includes, after the step ofapplying the composition, a step of raising the temperature of thekeratin fibres, using a heating means, to a temperature of between 110°C. and 250° C.

Advantageously, an iron is used as heating means.

For the purposes of the present invention, the term “iron” means adevice for heating keratin fibres that places the said fibres and theheating device in contact, the end of the iron that comes into contactwith the hair generally having two flat surfaces. These two flatsurfaces may be metallic. They may be smooth or crinkled.

As examples of irons that may be used in the process according to theinvention, mention may be made of flat irons of any type, and inparticular, in a non-limiting manner, those described in patents U.S.Pat. Nos. 5,957,140 and 5,046,516.

The iron may be applied by successive separate touches of a few seconds,or by gradually moving or sliding it along the locks.

Preferably, in the process according to the invention, the iron isapplied by continuous movement from the root to the end, in one or morepasses.

The process according to the invention may also include an additionalstep of partial predrying of the keratin fibres before the step ofraising the temperature, so as to avoid substantial evolution of steamthat might burn the stylist's hands and the individual's scalp. Thispredrying step may take place, for example, using a hairdryer, a hood oralternatively by drying in the open air.

The invention especially concerns processes in which the compositioncomprises at least one of the following combinations:

-   -   at least one denaturing agent is a guanidine corresponding to        formula (III) and at least one denaturing agent corresponds to        formula (V),    -   at least one denaturing agent is a urea corresponding to        formula (I) and at least one denaturing agent corresponds to        formula (III),    -   at least one denaturing agent is a urea corresponding to        formula (I) and at least one denaturing agent corresponds to        formula (V).

The invention also relates to a kit comprising at least:

-   -   one heating means that affords a temperature of between 110 and        250° C.,    -   one hair-relaxing composition containing at least two denaturing        agents.

The invention also relates to a kit comprising at least:

-   -   one heating means that affords a temperature of between 110 and        250° C.,    -   a first hair-relaxing composition containing at least one        denaturing agent,    -   a second hair-relaxing composition containing at least one        denaturing agent.

The invention may be understood more clearly with the aid of thenon-limiting examples that follow, which constitute preferentialembodiments of the compositions according to the invention.

The compositions may be applied as a mixture (see Example 1 and 2) orsuccessively (see Example 3).

EXAMPLE 1

A simplified hair-relaxing composition is prepared, containing a mixtureof guanidine hydrochloride at a concentration of 2 M and of pyruvic acidat a concentration of 2 M, in water, as hair-relaxing active agent. Thiscomposition is applied to naturally curly African hair for 15 minutes ata temperature of 40° C., and the hair is then rapidly towel-dried.

Lock-by-lock straightening of the head of hair is then performed using aflat iron heated to 180° C., for 10 to 15 seconds. The hair isefficiently relaxed and feels soft.

EXAMPLE 2

A simplified hair-relaxing composition is prepared, containing a mixtureof guanidine hydrochloride at a concentration of 4 M and of urea at aconcentration of 4 M, in water, as hair-relaxing active agent. Thiscomposition is applied to naturally curly African hair for 15 minutes ata temperature of 40° C., and the hair is then rapidly towel-dried.

Lock-by-lock straightening of the head of hair is then performed using aflat iron heated to 180° C., for 10 to 15 seconds. The hair isefficiently relaxed and feels soft.

EXAMPLE 3

A simplified hair-relaxing composition is prepared, containing urea at aconcentration of 2 M in water, as hair-relaxing active agent. Thiscomposition is applied to naturally curly African hair for 15 minutes ata temperature of 40° C., and the hair is then rapidly towel-dried. Asecond simplified hair-relaxing composition is prepared, containingpyruvic acid at a concentration of 2 M, in water, as hair-relaxingactive agent. This composition is applied to the same hair for 15minutes at a temperature of 40° C., and the hair is then rapidlytowel-dried. Lock-by-lock straightening of the head of hair is thenperformed using a flat iron heated to 180° C., for 10 to 15 seconds. Thehair is efficiently relaxed and feels soft.

The invention claimed is:
 1. A process for straightening the hair,comprising: (i) applying to the hair a composition comprising at leasttwo denaturing agents, and (ii) raising the temperature of the hair,using a heating means at a temperature ranging from 110° C. to 250° C.2. The process according to claim 1, wherein the pH of the compositionis less than
 9. 3. The process according to claim 1, wherein thecomposition comprises an overall concentration of denaturing agentsranging from 2 M to 8 M.
 4. The process according to claim 1, whereinthe temperature ranges from 140° C. to 220° C.
 5. The process accordingto claim 1, wherein the molar mass of the denaturing agents ranges from40 g/mol to 600 g/mol.
 6. The process according to claim 1, wherein thedenaturing agents are chosen from ureas, guanidines, α-hydroxy acid, andα-keto acid derivative, mono-, di-, tri- or polyhydroxylated aromaticderivatives, cyclic or linear amides, surfactants or detergents,amidines, thioureas, urethanes, alcohols, polyols, amine oxides, metalsalts, sulfamides, carboxylic acids, amino acids, and nitrogenousheterocycles of the imidazole or triazole family.
 7. The processaccording to claim 1, wherein at least one of the denaturing agents ischosen from ureas.
 8. The process according to claim 7, wherein theureas are chosen from ureas of formula (I):

wherein: R1, R2, R3 and R4 are independently chosen from: (a) hydrogen;and (b) linear or branched C1-C4 lower alkyl and alkenyl radicals,optionally substituted with a radical chosen from hydroxyl, amino,dimethylamino, carboxyl, carboxamide, and N-methylcarboxamide radicals,when R1, R2 and R3 are hydrogen, R4 may also denote a radical chosenfrom carboxamide; methoxy; ethoxy; 1,2,4-triazolyl; cyclopentyl;methoxy-carbonyl; ethoxycarbonyl; CO—CH═CH—COOH; phenyl optionallysubstituted with a chlorine atom or a hydroxyl radical; benzyl; and2,5-dioxo-4-imidazolidinyl radicals, when R1 and R2 are hydrogen, R3 andR4 may also form, together with the nitrogen atom that bears them, aring chosen from piperidine, 3-methylpyrazole, 3,5-dimethylpyrazole, andmaleimide rings, and R1 and R2 and R3 and R4 may also form, togetherwith the nitrogen atom that bears them, an imidazole ring.
 9. Theprocess according to claim 1, wherein at least one of the denaturingagents is a guanidine of formula (III):

wherein: R1, R2, R3, R4, and R5 are independently chosen from: (a)hydrogen; and (b) linear or branched C1-C4 lower alkyl and alkenylradicals, optionally substituted with one or two radicals chosen fromhydroxyl, amino, dimethylamino, methoxy, ethoxy, carboxyl, carboxamide,N-methylcarboxamide, and SO₃H radicals, when R1, R2, R3, and R4 arehydrogen, R5 may also denote a radical chosen from acetyl; chloracetyl;carboxamide; methoxy; ethoxy; 1,2,4-triazolyl; cyclopentyl;methoxycarbonyl; ethoxycarbonyl; CO—CH═CH—COOH; phenyl optionallysubstituted with a chlorine atom or a hydroxyl radical; benzyl;thiazolidone; benzimidazole; benzoxazole; benzothiazole; andC(═NH)—NR6R7 radicals, wherein R6 and R7 are independently chosen fromhydrogen and linear or branched C1-C4 lower alkyl radicals, optionallysubstituted with one or two radicals chosen from hydroxyl, amino,dimethylamino, carboxyl, carboxamide, and N-methylcarboxamide radicals;or alternatively a phenyl radical, when R1, R2, and R3 are hydrogen, R4and R5 may also form, together with the nitrogen atom that bears them, aring chosen from pyrrolidine, piperidine, pyrazole, and 1,2,4-triazolerings optionally substituted with one or two radicals chosen fromhydroxyl, amino, and carboxyl radicals, and when R1 and R2 are hydrogenand R4 is hydrogen or methyl, R3 and R5 may also together form a5-membered ring optionally containing an oxo group and the organic ormineral salts thereof.
 10. The process according to claim 1, wherein atleast one of the denaturing agents is an α-keto acid derivative offormula (V):

wherein R5 is chosen from H, COOH, linear or branched C1-C6 alkylradicals optionally substituted with a radical chosen from OH, COOH, andBr; phenyl and benzyl radicals optionally substituted with a radicalchosen from OH and COOH; indolyl radicals, and a radical of thefollowing formula:

and the stereoisomers, organic and mineral salts and solvates thereof.11. The process according to claim 10, wherein at least one of thedenaturing agents is: pyruvic acid 2-ketobutyric acid β-hydroxypyruvicacid 3-methyl-2-oxobutyric acid 2-oxovaleric acid ketomalonic acid3-methyl-2-oxovaleric acid trimethylpyruvic acid oxoacetic acid2-ketoglutaric acid benzylformic acid 2-oxooctanoic acid 2-oxoadipicacid phenylpyruvic acid bromopyruvic acid 2-ketopimelic acid4-hydroxyphenylpyruvic acid 3-indoleglyoxalic acid imidazolopyruvic acidHCl 2-keto-L-gulonic acid 2-carboxy-α-oxobenzeneacetic acid3-indolepyruvic acid 2-ketoglutaric acid dihydrate pyruvamideN-methylpyruvamide N-ethylpyruvamide N,N-dimethylpyruvamideN-2-hydroxyethylpyruvamide or a stereoisomer, organic or mineral salt,or solvate thereof.